Pros: It’s a lightweight utility that runs pretty much silently in the background; the only times we really noticed a system performance hit was in the middle of a large scan, and that was with several other memory-hungry applications running.

Cons: It’s very Mac-specific; it knows nothing about Windows viruses, so those could still be passed on (by, say, infected email messages). Your Mac would be safe, but you could be inadvertently infecting others.

Verdict: Certainly better than no security, but not quite a complete virus-blocking solution.